The proposed research is concerned with studying the perceptual information which supports expressive facial communications. By employing insights offered by experimental, social and perceptual psychologists, facial surgeons and artists, the facial surface will be studied in terms of its ability to provide invariant expressive information, across different senders, across the same sender at different times, and across different viewers or receivers. The methodology being employed requires that the facial surface be modeled in different ways so that different types and amounts of stimulus information is being presented to viewers. Viewers' ratings of the facial models determine how successsful or effective the models are in providing expressive information. Such procedures should allow for the development of a notation or measurement system which defines the perceptual or stimulus-based information specifying both different types of facial expressions, and the intensity of these expressions. Achieving this long-term objective will both allow us to more fully understand the process of affective facial communication, and may provide insights regarding the social functions of faces to clinicians (i.e. facial surgeons, orthodontists) who engage in treatment and planning decisions involving facial remodeling.